Cloudflare Challenge cf_clearance Cookie Guide

When Cloudflare flags a visitor as suspicious, it serves an interstitial challenge page. Once solved, the browser receives a cf_clearance cookie that grants access for the session. This guide explains how the challenge flow works and how CaptchaAI handles it.

How Cloudflare Challenge pages work

1. User requests a Cloudflare-protected page
2. Cloudflare evaluates risk signals (IP reputation, headers, TLS fingerprint)
3. If flagged, Cloudflare returns a 403 or 503 with a JavaScript challenge page
4. The challenge page runs browser checks and may present a Turnstile widget
5. On success, Cloudflare sets cf_clearance and redirects to the original URL
6. Subsequent requests with the cookie pass through without challenge

The cf_clearance cookie

The cookie is tied to several factors:

• IP address — Using the cookie from a different IP usually fails
• User-Agent — Must match the UA used during challenge solving
• TLS fingerprint — Some configurations bind to the TLS ClientHello

Challenge types

Cloudflare serves different challenge levels:

CaptchaAI solves all three types through the Cloudflare Challenge solver.

Solving with CaptchaAI

Python

import requests
import time

API_KEY = "YOUR_API_KEY"
TARGET_URL = "https://example.com/protected-page"

# Submit Cloudflare Challenge task
resp = requests.post("https://ocr.captchaai.com/in.php", data={
    "key": API_KEY,
    "method": "turnstile",
    "sitekey": "0x0000000000000000000000",  # may be generic for CF challenge
    "pageurl": TARGET_URL,
    "json": "1",
}).json()

if resp["status"] != 1:
    raise Exception(f"Submit error: {resp['request']}")

task_id = resp["request"]
print(f"Task ID: {task_id}")

# Poll for result
for _ in range(30):
    time.sleep(5)
    result = requests.get("https://ocr.captchaai.com/res.php", params={
        "key": API_KEY, "action": "get", "id": task_id, "json": "1"
    }).json()

    if result["status"] == 1:
        token = result["request"]
        print(f"Token received: {token[:50]}...")
        break
    if result["request"] != "CAPCHA_NOT_READY":
        raise Exception(f"Error: {result['request']}")

JavaScript

const axios = require('axios');

const API_KEY = 'YOUR_API_KEY';
const TARGET_URL = 'https://example.com/protected-page';

const submit = await axios.post('https://ocr.captchaai.com/in.php', null, {
  params: {
    key: API_KEY,
    method: 'turnstile',
    sitekey: '0x0000000000000000000000',
    pageurl: TARGET_URL,
    json: 1,
  }
});
const taskId = submit.data.request;

// Poll
let token = null;
for (let i = 0; i < 30; i++) {
  await new Promise(r => setTimeout(r, 5000));
  const poll = await axios.get('https://ocr.captchaai.com/res.php', {
    params: { key: API_KEY, action: 'get', id: taskId, json: 1 }
  });
  if (poll.data.status === 1) {
    token = poll.data.request;
    break;
  }
}
console.log(`Token: ${token.substring(0, 50)}...`);

Using the solved token

After solving, inject the token into the challenge page to obtain cf_clearance:

# With Selenium
from selenium import webdriver

driver = webdriver.Chrome()
driver.get(TARGET_URL)  # Load the challenge page

# Inject token into Turnstile response field
driver.execute_script("""
    const input = document.querySelector('input[name="cf-turnstile-response"]');
    if (input) input.value = arguments[0];

    // Trigger form submit or callback
    const form = document.querySelector('form');
    if (form) form.submit();
""", token)

# Wait for redirect and extract cookies
import time
time.sleep(3)
cookies = driver.get_cookies()
cf_clearance = next(
    (c for c in cookies if c['name'] == 'cf_clearance'), None
)
if cf_clearance:
    print(f"cf_clearance: {cf_clearance['value'][:30]}...")

Reusing the cookie

session = requests.Session()
session.cookies.set("cf_clearance", cf_clearance["value"], domain=".example.com")
session.headers.update({
    "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36"
})

# Now access protected pages
resp = session.get("https://example.com/api/data")
print(resp.status_code)  # 200

Cookie lifetime and refresh

The cf_clearance cookie expires. Plan for re-solving:

import datetime

def is_cookie_valid(cookie):
    if not cookie:
        return False
    expiry = cookie.get("expiry", 0)
    return datetime.datetime.now().timestamp() < expiry - 60  # 60s buffer

def get_or_refresh_clearance(driver, target_url, solve_func):
    cookies = driver.get_cookies()
    cf = next((c for c in cookies if c["name"] == "cf_clearance"), None)
    if is_cookie_valid(cf):
        return cf["value"]

    # Re-solve
    token = solve_func(target_url)
    # ... inject and extract new cookie

Troubleshooting

FAQ

Can I share cf_clearance between different machines?

Only if they share the same IP and you match the User-Agent string. Cloudflare often ties the cookie to the originating IP.

How long does cf_clearance last?

Typically 30 minutes to 24 hours, depending on the site owner's Cloudflare configuration.

Solve Cloudflare Challenge pages with CaptchaAI

Get your API key at captchaai.com.

Related guides

• Cloudflare Turnstile Sitekey Extraction
• Turnstile vs hCaptcha vs reCAPTCHA
• Cookies for Better Solve Rates